Fuel additive composition for stabilising blends of ethanol and a hydrocarbon

ABSTRACT

The present invention provides a fuel additive composition for stabilizing blends of ethanol and a hydrocarbon boiling in the gasoline or diesel range, comprising: a) 0.1-10% of Cashew Nut Shell Liquid (CNSL) derivative(s) or mixtures thereof of formula (I) where m=0-12, n=0, 2, 4 &amp; 6 and b) 0.1-10% of an organic co-solvent depending upon the percentage composition of diesel and ethanol blend.

FIELD OF THE INVENTION

This invention relates to a fuel additive composition for stabilisingblends of ethanol and a hydrocarbon boiling in the gasoline and dieselrange.

BACKGROUND OF THE INVENTION

Much research, efforts and time have been expended to produce fuelcompositions for internal combustion engines which show significantdecreases upon combustion of toxic exhaust gases or vapors, particulate,smoke, and the like without sacrifice of engine performance orefficiency. It is currently known by those skilled in the art that theintroduction of oxygenates into fossil fuels contributes to betterburning and the reduction of toxic exhaust emission. Ethanol is one suchoxygenate which, when used with gasoline for instance, reduces toxicemissions.

A problem, however is that ethanol attracts water and will separate fromgasoline in the presence of certain amounts of water condensation.Another problem is that ethanol is generally denatured using methanol,which exacerbates the problem of water separation and producesunacceptable solvency levels, such that ethanol/methanol/gasolinemixtures cannot be transported through existing pipelines. Anotherproblem associated with using ethanol as an oxygenate is that ethanol,as well as methanol and other water-soluble alcohols, will not mix atall with less refined fossil fuels, such as diesel fuel or otherdistillate fuels like kerosene.

Conventional diesels, derived from crude petroleum, are used in avariety of applications, such as in transportation, power generation andthe like.

Due to non-renewable nature of hydrocarbon fuels, considerable attentionhas been focused on development of alternate fuel sources. Oxygenatedfuels containing ethanol or water have now been considered as thepotential hybrid fuels and have gained the technical acceptance. Thefavourable economics of ethanol production and its increasedavailability combined with the beneficial effect on emissions has beenthe main factor behind development of ethanol-diesel blends. Thus, forthe purpose of economics, combustion properties and renewal nature,ethanol is widely being used in hybrid diesel formulations which arealso called ‘oxydiesel’.

While 5-10% anhydrous ethanol is miscible in diesel at room temp (25°C.), trace amount of water or lower temperature cause immediateseparation of the ethanol from the blends. Additionally, at lowertemperatures, the ability of blend to tolerate moisture is much less andphase separation results. This separation of ethanol-water from thehydrocarbon body is is undesirable as it could cause erratic combustionand severe corrosion in the fuel delivery system. Another major problemof making ethanol-diesel blends is of operational nature. This blendmaking process is energy intensive and it is very difficult tohomogenise the blend.

Emulsion or micro emulsions containing hydrocarbon liquid in thecontinuous phase and alcohol or water in a dispersed phase have beendescribed in a number of patents. These emulsions need a stabiliserwhich generally acts like an emulsifier.

A PCT application WO 9907465 by Apace research of Australia described anemulsifier, which is a block co-polymer of styrene or substitutedstyrene with ethylene oxide. Additionally, a coupler is also necessarywhich is chemically a block co-polymer of styrene or substituted styrenewith other hydrocarbons like butadiene. EP patent 0089147 describes theuse of block ethylene oxide-styrene copolymer for emulsifying alcoholsin diesel fuel. Another PCT application WO 0031216 describes a ethanolsolubilised diesel fuel composition.

PCT application WO 9935215 describes a additive composition also used asa fuel composition comprising water soluble alcohols. A German patent(DE 3525124, 1987) reported an emulsifier for making diesel-ethanolblends. The emulsifier was prepared by reaction of oleic acid withethoxylated oleylamine.

U.S. Pat. Nos. 6,190,427 and 6,017,369 describe diesel fuel compositionsstabilised by a mixture of fatty acid alcohols and a polymeric material.Another U.S. Pat. No. 4,451,265 describes diesel fuel-aqueous alcoholmicroemulsions based on a dimethylethanol amine surfactant system. A USpatent (256206, 1981) describes a surfactant system containingN,N-dimethyl ethanol amine and long chain fatty acid.

Cashew nut shell liquid (CNSL) occurs as a reddish brown viscous liquidin the soft honeycomb structure of the shell of cashewnut, a plantationproduct obtained from the cashew tree, Anacardium Occidentale L. Nativeto Brazil, the tree grows in the coastal areas of Asia & Africa.Cashewnut attached to cashew apple is grey colored, kidney shaped and2.54 cm long. The shell is about 0.3 cm thick, having a soft leatheryouter skin and a thin hard inner skin. Between these skins is thehoneycomb structure containing the phenolic material popularly calledCNSL. Inside the shell is the kernel wrapped in a thin brown skin, knownas the testa.

The nut thus consists of the kernel (20-25%), the shell liquid (20-25%)and the testa (2%), the rest being the shell. Natural CNSL, extractedwith low boiling petroleum ether, contains about 90% anacardic acid andabout 10% cardol. Natural CNSL, on distillation, gives the pale yellowphenolic derivatives, which are a mixture of biodegradable unsaturatedm-alkenylphenols, including cardanol. Catalytic hydrogenation of thesephenols gives a white waxy material, predominantly rich intetrahydroanacardol.

CNSL and its derivatives have been known for producing high temperaturephenolic resins and friction elements, as exemplified in U.S. Pat. Nos.4,395,498 and 5,218,038. Friction lining production from CNSL is alsoreported in U.S. Pat. No. 5,433,774. Likewise, it is also known to formdifferent types of friction materials, mainly for use in brake liningsystem of automobiles and coating resins from CNSL. U.S. Pat. No.6,229,054 describes a process for hydroxyalkylation of cardanol withcyclic organic carbonates. CNSL derivatives have also been used formetal extraction, as exemplified in U.S. Pat. No. 4,697,038. In anotherU.S. Pat. No. 4,352,944, mannich bases of CNSL have been described.

However, the first application of CNSL in making lubricating oiladditives was disclosed by us in U.S. Pat. Nos. 5,910,468 and 5,916,850.U.S. Pat. No. 6,339,052 also describes lubricant compositions forinternal combustion engines based on additives derived from cashew nutshell liquid.

Ethoxylated alcohols have been used in past as a stabilising emulsifyingadditives for making stable ethanol-petroleum fuel compositions.

For example, a U.S. Pat. No. 6,080,716 of 2000 describes a surfactantwhich is made by reaction of aliphatic alcohol with ethylene oxide. Thenon-ionic ethoxylated surfactant, as stabilising additives are preparedfrom reaction of aliphatic alcohol with ethylene oxide and are alsoavailable commercially e.g., Neodol 91-2.5 from Shell chemicals. Thus,Neodols prepared from reaction of C₉ to C₁₁ alcohol with ethylene oxideto give products having average number of ethylene oxide from 2.5 to 10per mole of alcohol (U.S. Pat. No. 6,183,524 of 2001) have been used asthe stabilising additives.

OBJECTS AND SUMMARY OF THE INVENTION

The object of the invention is to obviate the above drawbacks bydeveloping an additive composition which can be used to make stablefuel-alcohol mixtures.

Further, object of the invention is to propose an additive compositionwhich is effective at lower dosage.

Still further objective is to minimize the cost of the coupler (additivecomposition) by selecting appropriate inexpensive raw materials.

Another object of the invention is to develop an emulsifier based onnatural occurring biodegradable and abundantly available Cashew NutShell Liquid (CNSL) for preparing the additive composition.

To achieve said objectives this invention provides a fuel additivecomposition for stabilizing blends of ethanol and a hydrocarbon boilingin is the gasoline or diesel range, comprising:

-   -   a) 0.1-10% of Cashew Nut Shell Liquid (CNSL) derivative(s) or        mixtures thereof of formula:        -   where m=0-12        -   n=0, 2, 4 & 6 and    -   b) 0.1-10% of an organic co-solvent    -   depending upon the percentage composition of diesel and ethanol        blend

In the above fuel additive composition, m=1-12 and n=2, 4, 6, and saidCNSL derivatives are ethoxylates of CNSL.

In the above fuel additive composition m=1-12 and n=0, and said CNSLderivatives are ethoxylates of partially hydrogenated CNSL.

In the above fuel additive composition m=0 and n=0, and said CNSLderivative is partially hydrogenated CNSL.

In the above fuel additive composition m=0 and n=2, 4, 6, and said CNSLderivative is technical CNSL.

The said ethoxylated CNSL derivatives are reaction product of technicalCNSL and an ethoxylating agent.

The said ethoxylated CNSL derivatives are reaction product of partiallyhydrogenated CNSL and an ethoxylating agent.

The said organic co-solvent is selected from the group of alcohol, fattyacid ester, ester and the mixture thereof.

The said organic co-solvent is a normal or branched chain primary orsecondary alcohol having a carbon number of 3 to 16.

The said alcohol is present in an amount of 0.1-5 vol %.

The said fatty acid esters are methyl or ethyl esters of Jatropha carcusoil, soyabean oil, sunflower oil and karanjia oil.

The said ester is present in an amount 0.2% to 4% based upon thestabilizing additive composition.

The said mixture comprises CNSL and ethoxylated CNSL.

The said mixture comprises CNSL and hydrogenated CNSL.

The said mixture comprises ethoxylated CNSL and ethoxylated hydrogenatedCNSL.

The said mixture comprises CNSL, hydrogenated CNSL and ethoxylated CNSL.

The blends of ethanol and hydrocarbon comprising ethanol 1-15% anddiesel 85-99%.

The ethanol is having 0 to 1.0% by wt. of water and is referred to asanhydrous ethanol.

The ethanol containing higher than 1.0% water is referred to as hydrousethanol.

The said fuel additive composition further includes cetane improver tomeet the requirement as laid in the diesel fuel specification.

The said fuel additive composition further includes known corrosioninhibitors to control corrosion to the metallic parts on the fuel sidecomponents.

The present invention also provides a fuel composition comprising of (i)a hydrocarbon based fuel boiling in the gasoline or diesel range (ii)ethanol and (iii) fuel additive composition of the instant invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides for a fuel stabilising additive mixture suitablefor blending hydrocarbon fuel-alcohol mixtures. The invention describesa fuel additive useful for making stable hydrocarbon fuel alcohol blendsfor use in internal combustion engines. Ethanol-petroleum fuel blendsdirectly address vehicle emissions, transport fuel security and supplyissues. In addition to reducing currently regulated emissions, therenewable ethanol content of these fuels can result in net reduction inthe emission of carbon dioxide. However, the amount of hydrous oranhydrous ethanol which can be added to petroleum fuels is very low astheir miscibility is low and the layer of ethanol separates out. Theproblem of separation of ethanol from the ethanol-petroleum fuel blendsbecome more aggravated specially at low temperatures. To make stableethanol-petroleum fuel blends, addition of stabilising additives isnecessary. The hybrid fuels prepared incorporating the additives mixtureof the invention result in lower emissions and are stable over alongperiod of storage, more than 6 months, at the temperatures equivalent tothe pour point of the diesel.

The inventive stabilising additive consists of either cashew nut shellliquid (CNSL), technical or hydrogenated, or the ethoxylate of technicalor hydrogenated CNSL, or the mixtures thereof.

It has been observed that ethoxylated CNSL is a very potent stabilisingadditive useful for making stable ethanol-petroleum hybrid fuel whichare suitable as fuel in internal combustion engines. The natural orhydrogenated CNSL are ethoxylated using a known ethoxylating agent, suchas ethylene oxide. The overall degree of ethoxylation of CNSL is variedby controlling the ratio of cashew nut shell liquid and ethylene oxide,the reaction temperature and pressure. Higher degree of ethoxylationresults in better water solubilisation capacity which is desirable.However very high degree of ethoxylation leads to solidification of theproduct and therefore intermediate ethoxylation is desirable. It hasbeen discovered in the present invention that CNSL having anethoxylation content of 3 to 10 is most suitable for use as thestabilising additive for making ethanol-diesel blends. The ethoxylatedCNSL of the present invention is far superior in stabilising efficacyvis-à-vis commercially available ethoxylated alcohols, e.g., Neodols.The higher efficacy of ethoxylated CNSL has resulted in its lower dosageand thus better cost-economics.

It has also been observed that technical CNSL as such or afterhydrogenation is also a very potent coupling additive for making stablefuel-ethanol blends. The stabilising effect is further augmented, if amixture of technical CNSL or hydrogenated CNSL and their ethoxylates areused. This capability of technical CNSL, hydrogenated CNSL and theirethoxylates to act as solubilising additive for making stablehydrocarbon fuel-ethanol blends has been observed for the first time.This observation is of particular importance as it will bring down thecost of stabilising coupler to a very significant level as the basicmaterial, i.e., CNSL is of low cost and abundantly available. A highdegree of biodegradability of CNSL and its ethoxylates is an additionaldesirable benefit.

The fuel compositions described in this invention contains ethanol.Ethanol is typically produced by fermentation of sugars derived fromsugar residue, grains or from biomass. Ethanol suitable for use inaccordance with the invention preferably includes fuel grade ethanolderived from yeast or bacterial fermentation of six carbon sugarsextracted from corn, sugarcane or sugar beet. Fuel grade ethanol may beproduced from lingocellulosic material, rice husks, bagasse etc byacid/base or enzymatic hydrolysis.

The suitable fuel grade ethanol in accordance with the present inventionmay be having up to 1.0% w/w water and this ethanol is referred asanhydrous ethanol. Alternatively, other type of ethanol, suitable foruse in this invention may contain higher amount of water, i.e., morethan 1.0% w/w and is referred as hydrous ethanol.

The miscibility of ethanol in diesel fuel is limited primarily becauseof differences in the polarity. The polarity of diesel is a function ofits molecular composition and its electro chemical properties. Themolecular composition of diesel depends upon the type of distillatestreams it contains, the refining process and more importantly on thecrude source.

Therefore, the inherent capability of any given diesel to solubiliseethanol is fixed. Diesel contains different hydrocarbon group types e.gparaffins, isoparrafins, naphthenes, olefins, aromatics andheterocyclics. Each of these groups have different polarity (dieletricconstants). Aromatics, olefins and heterocyclics have higher polaritiesthan paraffins, isoparraffins and naphthenes. The components with higherdielectric constant (e.g. aromatics) can easily have dipole-dipoleinteraction, with polar ethanol. This results in solubilisation ofethanol in diesel. The diesel with higher amount of aromatics cansolubilise higher amount of ethanol. For this reason, diesel fractionsobtained from hydrocracker and having lower aromatics, are very poor insolubilising ethanol. In the presence of water, the solubilising powerof a given diesel is further depressed. This is explained by the higherpolarity of water as compared to ethanol and its preferential dipoleinteraction with the polar components of diesel.

The overall ability of a given diesel to solubilise ethanol can bemanipulated with the help of addition of external additives calledcouplers. These couplers are believed to act in two different ways.Firstly, these could act like a surfactant to bring in polar water andethanol molecules into the hydrocarbon phase of diesel. These couplersare so designed that they have a moderately polar end and a non-polartail. The polar head gets dissolved in the water or ethanol by H-bondingand the non-polar tail gets solubilised in the hydrocarbon phase(diesel).

The chemical couplers act as a bridge between polar water/ethanol andnon-polar hydrocarbon phase. Thus chemically couplers like alcoholethoxylates, functionalised polymers, long chain alcohols which containpolar head and non-polar chains are useful and have been used in theprior art.

The other method of solubilising ethanol in diesel is by the use oforganic co-solvents. These are chemical compounds which haveintermediate polarity between low polar diesel and higher polarityethanol. These are used to increase the overall polarity of diesel sothat it could solubilise higher amount of ethanol. Such co-solvents areselected from C₄-C₈ alcohols, C₁₀-C₂₀ esters etc.

If there is no water present in the diesel fuel/ethanol mixture, i.e.,the ethanol used is anhydrous, then the solubilising power of the dieselis higher. However, when water even in trace amount is present in themixture, then the available dipole-dipole interaction is preferredbetween water and polar components of diesel, instead of ethanol. Thus,the presence of water in the diesel fuel/ethanol mixture reduces thesolubilisation of ethanol in diesel. The presence of water and itseffect on the mixture is exacerbated with the lower temperature ofmixture, especially below 4° C. Because water, unlike any fuelcomponent, can exist in distinctly different physical form at or nearits freezing point. therefore, at lower temperatures the solubilisationof water/ethanol in diesel is difficult and opaque solutions areobtained.

The organic co-solvent used in the present invention is generallyselected from the polar compounds like alcohols, ethers or fatty acidesters. The main function of co-solvent is to enhance the overallpolarity of fuel so that ethanol and water are drawn into the system.Once ethanol and water are in the system, then the stabilising additivesolubilizes these with its surfactant action. Normal or branced alcoholhaving chain length of C₃ to C₁₀ are suitable. The most suitable alcoholmay be C₄ alcohol which is effective in lower dosage.

Organic esters of lower acids and fatty acid esters can also be used asco-solvents. However, though lower esters e.g. ethyl acetate are potentco-solvent but their lower flash points are limiting factor for theiruse in diesel fuel. Fatty acid esters derived from the base or acidcatalysed transestrification of natural oils have been found to beexcellent co-solvent. Apart from providing the necessary solvationpower, these esters also improve the overall lubricity of the dieselfuel, specially for fuels having very low level of sulphur (<200 ppm).

The fatty acid ethyl and methyl ester prepared from natural oils likeJatropha curcas, Karanjia, Sunflower and Soya oils were found to besuitable as co-solvent for making ethanol-diesel blends. The amount ofthese esters to be used in a blend depends upon the amount and waterlevel of ethanol to be blended. However, the effective range of thesefatty acid ester was 0.5-1.0% vol to 200-300 vol. of fuel.

Cetane index is the measure of combustability of diesel fuel in theinternal combustion engine. The value of cetane number is generallyspecified in the commercial specification of fuel and are different fordifferent countries. In India e.g the minimum cetane number is 48.

The ethanol-diesel blends generally fall short in the cetane number asthe ethanol does not contribute to the overall cetane of the hybridfuel. However, the cetane number of blended fuel can easily be boostedby adding small amount of cetane booster.

Organo nitrates e.g isopropyl nitrate or 2-ethyl hexyl nitrates whichare available commercially are suitable to enhance the cetane of theethanol blended hydrocarbon fuel. The amount of cetane booster presentin the blend is the function of cetane value of the particular dieselfuel and the amount of ethanol present in the particular fuelcomposition. Generally, lower the diesel fuel cetane value, higher theamount of the cetane booster. Similarly, because ethanol typically actsas a cetane depressent, the higher the concentration of ethanol in thehybrid fuel, more is the concentration of cetane booster.

Higher amount of dissolved water in the ethanol-diesel fuel may causecorrosion to the metallic parts specially on the fuel side components.This problem could be easily controlled by addition of corrosioninhibitors. Several classes of corrosion inhibitors are known for use infuels. However, it has been found that mercapto thiadiazole derivativesas described in U.S. Pat. No. 6,362,137 were the most effective in thesefuels. For hydrocarbon fuels, containing 5-10% of ethanol, an additionof 0.001 to 0.01% volume of the mercapto thiadiazole described in U.S.Pat. No. 6,362,137 are sufficient to provide necessary anti corrosionproperties.

The amount of CNSL, hydrogenated CNSL or ethoxylated CNSL to be usedwith a particular fuel depends upon the desired end specifications ofthe fuel the quality of ethanol and the amount of the ethanol to beblended. For example, if anhydrous ethanol is to be blended in dieselthen the amount of ethoxylated CNSL will be lower than if the ethanolwas hydrous. Due to various characteristics of hydrocarbon fuels, it isdifficult to provide a singular relationship to the amount of CNSL orethoxylated CNSL to be used. However, as a rough guide, to make 5-10%anhydrous ethanoldiesel blend which is stable up to −3° C., the volumeratio of additives to the fuel may be 1-2:100. The volume ratio forhydrous ethanol of the similar quantity may be 3-5:100.

The fuel composition of the invention provide a number of benefits. Forexample, the fuel composition remain stable over the range oftemperatures (from the pour point of diesel to about +50° C.) whichcovers both summer and winter conditions. Additionally, the fuelcomposition remains clear and transparent even in the presence of watercontamination of about 0.5-1.2% vol. The fuel also meets the minimumcetane number requirement as laid in the diesel fuel specification andthe fuel blends can be prepared within minutes without the need ofexpensive and energy intensive fuel blending equipment. Since theblended fuel has lower sulphur and aromatics as compared to the parentdiesel, the tail pipe sulphur emissions are low.

In order to evaluate the efficacy of the coupler or co-solvent tosolubilise ethanol in diesel, an experiment was specifically designed.In this set-up, to a fixed volume of diesel, different amounts ofcouplers/co-solvents were added. To the mixture thus obtained, ethanolwas gradually added with a burette, with continuous shaking. Appearanceof turbidity or layer separation was noticed in each experiment. Higherthe amount of ethanol, which could be added without causing turbidity orlayer separation, reflected the higher solubilising power of thecoupler/co-solvent. The results are presented in Table-1.

As is evident from Table-1, CNSL as such and its ethoxylated compoundsshow much enhanced power to solubilise ethanol in diesel. Thus, while0.5% v/v of ethoxylated CNSL could solubilise 14-16% v/v of ethanol isdiesel, whereas the commercially available ethoxylated alcohols, likeNeodol 91-2.5 or Tomoh 11-3 could solubilise only approximately 10.0%v/v of ethanol in diesel. Other commercial surfactants were even poor intheir solubilising power (6-8% v/v). The higher solubilising power ofCNSL, hydrogenated CNSL and ethoxylated CNSL which contains both polargroup (hydroxyl and aromatic ring) and a non-polar C₁₅ alkyl chain atmeta position. The effect of both coupler and co-solvent on thesolubilising power was also examined by these experiments. It was seenthat a combination of CNSL/hydrogenated CNSL/ethoxylated CNSL and theco-solvent was more potent than the mixture of any other surfactant withthe same co-solvent. Thus, while a mixture of 0.5% ethoxylated CNSL and1% isobutanol could solubilise 19.4% v/v of ethanol in a given diesel, amixture of other commercial ethoxylated alcohols with 1% isobutanolcould only solubilise approximately 8-12% of ethanol. TABLE 1 EthanolSolubilisation in Diesel in the presence of Co-Solvent Surfactant VolumeUsed 0.2 0.4 0.6 0.8 1.0 Surfactant Alcohol Volume Solubilised 1. CNSL5.8 7.0 9.0 9.9 11.2 2. Partially Hydrogenated CNSL 5.5 6.5 7.8 9.8 11.03. CNSL + Partially Hydrogenated 5.7 6.8 8.2 10.0 11.3 CNSL (1:1) 4. IsoButanol 3.6 4.4 5.0 5.4 5.8 5. Tert-Butanol 3.5 4.3 5.0 5.5 6.1 6. DecylAlcohol-6 Ethoxylate 2.5 2.3 1.4 1.8 1.9 7. Tri-decyl Alcohol-6Ethoxylate 3.5 3.2 3.6 3.8 3.9 8. Decyl Alcohol-6 Ethoxylate 2.5 1.0 0.70.6 0.4 9. Dioctyl phthalate 3.45 3.45 3.5 3.5 4.3 10. Dioctyltrimellitate 3.1 3.2 3.2 3.2 3.5 11. Methyl Ester of Rice Bran 3.1 3.33.3 3.6 4.0 Oil Fatty Acids 12. Methyl Ester 3.2 3.4 3.6 4.2 4.4 ofCastor Oil Fatty Acids 13. Ethyl ester of castor 3.8 4.3 5.5 6.3 7.0 oilfatty acids 14. NEODOL 91-2.5 Ethoxylate 4.2 4.4 4.6 4.8 4.9 15. TOMOH91-2.5 4.2 4.4 4.7 4.7 4.9 16. TOMOH 1-3 4.1 4.2 4.4 4.6 4.6 17. TOMOH25-3 4.3 4.2 4.2 4.4 4.4 18. TOMOH 23-3 4.4 4.2 4.3 4.5 4.7 19. CSNLEthoxylate - 3 6.2 7.1 9.3 10.1 11.4 20. CNSL Ethoxylate - 8 5.9 6.9 9.69.9 11.3 21. CNSL + CNSL 6.3 7.0 9.5 10.0 11.5 ethoxylate - 3 (1:1) 22.CNSL + partially hydrogenated 5.9 6.5 9.2 9.9 11.6 CNSL + CNSLethoxylate - 3 (1:1:1)** In all these experiments, 40 ml of diesel was taken. Without anyCoupler/Co-Solvent, Diesel could solubilise only 2.2 ml of anthydrousethanol. In the presence of 0.25% of co-solvent (tert-butanol), 40 ml ofdiesel could solubilise 2.9 ml of anhydrous ethanol.

Thus CNSL as such, after hydrogenation or preferably ethoxylated CNSLeither alone or in combination with co-solvents offer a potent couplerfor enhanced solubilisation of ethanol in diesel to give stablemixtures.

EXAMPLES

The following examples are provided to further illustrate the invention,but are not intended to limit the scope of the invention. Specifically,the following examples are provided to illustrate the composition,manufacture and physical characteristics of the inventive fuelcomposition containing ethanol and the inventive additives, which fullymeet the laid down physico-chemical specifications of the diesel fuel.

Example 1

Hydrocarbon fuel (900 ml) is placed in a 1 litre flask at ambienttemperature and pressure. Ethanol (80 ml) is added to the flask creatingan oil phase and an alcohol phase. A mixture of isobutanol (10 ml) andethoxylated cashew nut shell liquid (10 ml) is then added, a stopper isapplied to the top of the flask and the resultant mixture is shaken forabout one minute, to allow proper mixing of the liquids to take placeand a single phase to form. The hybrid fuel as obtained is stable at −3°C. for more than three months.

Example 2

Cashew nut shell liquid (12 ml) is added to n-butanol (8 ml) and ethylacetate (5 ml) with minimal stirring to form one phase. This is added toa two phase mixture of hydrocarbon fuel (900 ml) and ethanol (75 ml).The final blend is shaken for about one minute to form a single phase.The hybrid fuel as obtained is stable at −3° C. for more than threemonths.

Example 3

Hydrogenated cashew nut shell liquid (15 ml) and hydrocarbon fuel (885ml) are mixed together and ethanol (100 ml) is added slowly to thismixture. After completion of the addition of ethanol, the oxy dieselblend is shaken for about one minute, till a single phase is formed. Thehybrid fuel so obtained is stable over a long period without anyseparation of layers.

Example 4

Ethoxylate of distilled technical Cashew nut shell liquid (10 ml) andethanol (100 ml) are mixed together and hydrocarbon fuel (890 ml) isadded slowly to this mixture. After completion of the addition ofethanol, the oxy diesel blend is shaken for about one minute, till asingle phase is formed.

By adopting any of the above blending procedures, the following stablecompositions can be obtained. Product blends were made (as percentagev/v) as follows.

Composition 1:

-   Diesel: 85.0%-   Ethanol: 10.0%-   Cashew Nut Shell Liquid (CNSL): 1.0%-   Bio-Diesel: 4.0%    Composition 2:-   Diesel: 86.0%-   Ethanol: 12.0%-   Cashew Nut Shell Liquid (CNSL): 1.0%-   CNSL Ethoxylate with 3 ethylene oxide moieties: 1.0%    Composition 3:-   Diesel: 85.0%-   Ethanol: 12.0%-   Cashew Nut Shell Liquid (CNSL): 0.75%-   CNSL Ethoxylate with 5 ethylene oxide moieties: 0.75%-   Bio-Diesel: 1.5%    Composition 4:-   Diesel: 92.0%-   Ethanol: 6.0%-   Cashew Nut Shell Liquid (CNSL): 1.0%-   Bio-Diesel: 1.0%    Composition 5:-   Diesel: 85.0%-   Ethanol: 10.0%-   Cashew Nut Shell Liquid (CNSL): 1.5%-   Bio-Diesel: 2.5%-   n-Butanol: 1.0%    Composition 6:    Composition 6:-   Diesel: 92.0%-   Ethanol: 6.0%-   Cashew Nut Shell Liquid (CNSL): 1.2%-   Ethyl Acetate: 0.8%    Composition 7:-   Diesel: 85.0%-   Ethanol: 10.0%-   Cashew Nut Shell Liquid (CNSL): 2.0%-   CNSL Ethoxylate with 8 ethylene oxide moieties: 3.0%    Composition 8:-   Diesel: 85.0%-   Ethanol: 10.0%-   Partially hydrogenated Cashew Nut Shell Liquid (CNSL): 1.0%-   Bio-Diesel: 4.0%    Composition 9:-   Diesel: 80.0%-   Ethanol: 15.0%-   Cashew Nut Shell Liquid (CNSL): 2.0%-   Bio-Diesel: 2.0%-   CNSL Ethoxylate with 5 ethylene oxide moieties: 1.0%    Composition 10:-   Diesel: 84.0%-   Ethanol: 12.0%-   Cashew Nut Shell Liquid (CNSL): 1.5%-   Partially Cashew Nut Shell Liquid: 0.5%-   CNSL Ethoxylate having 3 ethylene oxide moieties: 2.5%    Composition 11:-   Gasoline: 85.0%-   Ethanol: 11.0%-   Cashew Nut Shell Liquid (CNSL): 1.0%-   Bio-Diesel: 3.0%    Composition 12:-   Gasoline: 90.0%-   Ethanol: 8.0%-   Cashew Nut Shell Liquid (CNSL): 1.0%-   CNSL Ethoxylate with 3 ethylene oxide moieties: 1.0%    Composition 13:-   Gasoline: 85.0%-   Ethanol: 12.0%-   Cashew Nut Shell Liquid (CNSL): 0.75%-   CNSL Ethoxylate with 5 ethylene oxide moieties: 0.75%-   Bio-Diesel: 1.5%    Composition 14:-   Gasoline: 90.0%-   Ethanol: 8.0%-   Cashew Nut Shell Liquid (CNSL): 0.5%-   CNSL Ethoxylate with 5 ethylene oxide moieties: 0.5%-   Bio-Diesel: 1.0%    Composition 15:-   Gasoline: 92.0%-   Ethanol: 7.5%-   Cashew Nut Shell Liquid (CNSL): 0.25%-   Tert-Butanol: 0.25%

All of the above compositions had a single phase demonstrating theeffectiveness of the use of Cashew nut shell liquid and Cashew Nut ShellLiquid Ethoxylates to blend hydrocarbon fuels with ethanol. Thesecompositions were tested at varying temperatures from −5° C., 0° C., 10°C., 15° C., 20° C., 25° C. & 30° C., which reflect typical operatingtemperatures for normal transport fuels and were not found to betemperature sensitive. In each of the compositions listed above, theblend of the diesel oil and ethanol is in one phase and the blend wasfound to operate satisfactorily as a fuel.

In addition to above primary components, cetane improver, lubricityadditive and corrosion inhibitor were added as per operationalrequirements. The addition of these components did not affect thestability of the diesel-ethanol-CNSL blends at varying temperatures.

1. A fuel additive composition for stabilizing blends of ethanol and ahydrocarbon boiling in the gasoline or diesel range, comprising: a)0.1-10% of Cashew Nut Shell Liquid (CNSL) derivative(s) or mixturesthereof of formula:

where m=0-12 n=0, 2, 4&6 and b) 0.1-10% of an organic co-solventdepending upon the percentage composition of diesel and ethanol blend.2. A fuel additive composition as claimed in claim 1, wherein m=1-12 andn=2, 4, 6, and said CNSL derivatives are ethoxylates of CNSL.
 3. A fueladditive composition as claimed in claim 1, wherein m=1-12 and n=0, andsaid CNSL derivatives are ethoxylates of partially hydrogenated CNSL. 4.A fuel additive composition as claimed in claim 1, wherein m=0 and n=0,and said CNSL derivative is partially hydrogenated CNSL.
 5. A fueladditive composition as claimed in claim 1, wherein m=0 and n=2, 4, 6,and said CNSL derivative is technical CNSL.
 6. A fuel additivecomposition as claimed in claim 2, wherein said ethoxylated CNSLderivatives are reaction product of technical CNSL and an ethoxylatingagent.
 7. A fuel additive composition as claimed in claim 3, whereinsaid ethoxylated CNSL derivatives are reaction product of partiallyhydrogenated CNSL and an ethoxylating agent.
 8. A fuel additivecomposition as claimed in claim 1 wherein said organic co-solvent isselected from the group of alcohol, fatty acid ester, ester and themixture thereof.
 9. A fuel additive composition as claimed in claim 1,wherein said organic co-solvent is a normal or branched chain primary orsecondary alcohol having a carbon number of 3 to
 16. 10. A fuel additivecomposition as claimed in claim 9, wherein said alcohol is present in anamount of 0.1-5 vol %.
 11. A fuel additive composition as claimed inclaim 8, wherein said fatty acid esters are methyl or ethyl esters ofJatropha carcus oil, soyabean oil, sunflower oil and karanjia oil.
 12. Afuel additive composition as claimed in claim 8, wherein said ester ispresent in an amount 0.2% to 4% based upon the stabilizing additivecomposition.
 13. A fuel additive composition as claimed in claim 1,wherein said mixture comprises CNSL and ethoxylated CNSL.
 14. A fueladditive composition as claimed in claim 1, wherein said mixturecomprises CNSL and hydrogenated CNSL.
 15. A fuel additive composition asclaimed in claim 1, wherein said mixture comprises ethoxylated CNSL andethoxylated hydrogenated CNSL.
 16. A fuel additive composition asclaimed in claim 1, wherein said mixture comprises CNSL, hydrogenatedCNSL and ethoxylated CNSL.
 17. A fuel additive composition as claimed inclaim 1, wherein blends of ethanol and hydrocarbon comprising ethanol1-15% and diesel 85-99%.
 18. A fuel additive composition as claimed inclaim 17, wherein ethanol is having 0 to 1.0% by wt. of water and isreferred to anhydrous ethanol.
 19. A fuel additive composition asclaimed in claim 17, wherein ethanol contains higher than 1.0% water bywt. and is referred as hydrous ethanol.
 20. A fuel additive compositionas claimed in claim 1, further includes cetane improver to meet therequirement as laid in the diesel fuel specification.
 21. A fueladditive composition as claimed in claim 1, further includes knowncorrosion inhibitors to control corrosion to the metallic parts on thefuel side components.
 22. A fuel composition comprising of (i) ahydrocarbon based fuel boiling in the gasoline or diesel range (ii)ethanol and (iii) fuel additive composition of claim 1.